In my 46 years of career, this is called a 'technician'. Has all sorts of experience, even engineers are envious of the job. At least, this is what i was called when I did this and held this position.
One particular job, as a technician, was at a pacemaker mfg company. The job was to keep all the high tech machines that made hybrid support devices, wirebonders, plasma cleaners, wire testing of 0.001" diameter gold wire, (many more) working and make improvements to them, as needed. This included adding, repairing or modifying existing mechanical or electronic systems. Spent ten years here(dream job for me).